High precision glass thinning: from micron level game to precision manufacturing revolution of industrial breakthrough
The “lightweight” demand of modern industry for glass has gone beyond simple size reduction and become an extreme game of material science, process control and engineering implementation. When the thickness of the cover glass of the folding screen mobile phone is 30 μ m (0.03 mm), and the surface accuracy of the optical elements of the lithography machine is required to be ± 0.1 μ m, the traditional thinning technology is facing unprecedented challenges. high-precision Glass thinning The core contradiction of is: How to maintain the balance between strength, optical performance and mass production feasibility while the thickness drops sharply?
1、 Technical Logic: Triple Game Behind Precision
- Breakthrough path of material limit
The essence of glass thinning is material removal, but the precision ceilings of different processes are different:- Chemical thinning : Relying on hydrofluoric acid etching, micron level removal is achieved through precise control of concentration (10-40%), temperature (20-30 ℃) and time (500-1000s). However, the reaction uniformity is difficult to guarantee, and the edge is prone to etching pits (Ra>50nm), which is only applicable to scenes with low precision requirements.
- Laser thinning : Femtosecond laser pulse (μ J level energy) realizes local gasification through non-contact cold processing, with cutting accuracy of ± 1 μ m and edge roughness<5nm. Its core advantage lies in programmability – selective area thinning of optical lenses to achieve asymmetric thickness control (such as correcting transparent image difference).
- Composite process breakthrough : The strategy of “progressive thinning+sectional strengthening” of China Building Materials Group Co., Ltd. is to pre thin the glass to 100 μ m and then carry out the first chemical strengthening, and continue to thin after establishing the surface compressive stress layer. This method reduces the microcrack propagation of 30 μ m ultra-thin glass by 50%, and increases the yield by 30%.
- Engineering art of stress management
The decrease of thickness directly leads to the square attenuation of bending strength (the strength of 1.6mm glass is only 25% of 3.2mm glass). High precision thinning must simultaneously solve strength collapse:- Ion exchange enhancement : Immerse 30 μ m glass into 350-450 ℃ molten potassium salt (KCl solution), form a pressure stress layer>700MPa on the surface through ion replacement, and the bending life exceeds 1 million times.
- Stress compensation design : Photovoltaic glass adopts honeycomb reinforced grid to reduce the deformation sensitivity of 1.6mm thin glass by 40% and resist the deformation of wind pressure and temperature difference.
- Control Paradigm of Mass Production Precision
The gap between laboratory parameters and mass production needs to be filled through closed-loop control:- Real time thickness feedback : The optical interferometer monitors the thickness fluctuation online (resolution 0.1 μ m), and dynamically adjusts the laser power or etching liquid flow.
- Taming of environmental factors : The temperature fluctuation of ± 1 ℃ can lead to the deviation of the resonant frequency of the quartz crystal vibration plate. The constant temperature workshop (± 0.5 ℃) and the active damping platform are required to suppress the resonance.
2、 Project implementation: crossing the valley of death in mass production
- Devil details of defect prevention and control
- The sensitivity of ultra-thin glass to dust increases exponentially. A dust particle with a diameter of 5 μ m attached to the glass surface may be amplified as a penetrating crack after hydrofluoric acid etching. The Grade 10 clean room (ISO Class 4) and electrostatic suspension transmission system become a rigid need, and the damage rate of taking and discharging is reduced to<0.1%.
- In chemical thinning, the introduction of alkali metal ions (K+/Li+) can optimize the etching uniformity. The pit inhibiting liquid developed by Hainan University reduces the defect rate caused by micro scratch of incoming materials by 60%.
- Revolutionary breakthrough in integrated processing
The traditional step-by-step process (thinning before chamfering) leads to yield loss of more than 30%. Bourne Optics Integrated process of laser engraving+chemical etching Subversion process:- Step1 : Laser engraving chamfer structure inside the glass (circular path)
- Step2 : chemical etching to remove the surface layer, depth ≥ the minimum distance from the chamfer edge to the surface
- Step3 : The split is made of ultra-thin glass with chamfer
This technology reduces the times of handling and positioning by 70%, shortens the processing cycle by 50%, and improves the edge strength by 200%.
3、 Industrial value: precision driven scene revolution
- Folding screen phone : 30 μ m ultra-thin glass (UTG) with light transmittance>90% and hardness of 600HV has become the core cover material of Samsung Galaxy Z Flip and Huawei Mate X. However, the yield of mass production is only 30-50% at present, and the cost is as high as 800 dollars/square meter.
- High end optics ：
- After the photoresist mirror is thinned to 1.6mm, the surface shape accuracy needs to maintain λ/20 (λ=632nm), and the cumulative error of film thickness is less than 1 ∨ (0.1nm).
- AR glasses lenses are reduced to 0.5mm, and the field angle is expanded to 120 ° with anti reflection coating, and the weight is reduced by 40%.
- Photovoltaic module lightweight : The 2.0mm photovoltaic glass has 37% less weight than the 3.2mm version, but it needs to resist wind pressure deformation through semi tempering process and edge enhancement design. At present, 1.6mm glass is limited to roof distributed projects, and ground power stations still rely on 2.0mm glass to ensure reliability.
4、 Future Battlefield: Race for Life and Death with Nanometer Precision
The current technical bottlenecks are clearly visible:
- Cost dilemma : In the cost of UTG parent glass, the thinning process accounts for more than 50%, and the waste liquid treatment of hydrofluoric acid etching further drives up the expenditure.
- Environmental challenges : Highly toxic hydrofluoric acid (HF) etching solution accelerates the development of acid free process, and plasma etching technology becomes an alternative direction.
- Flexibility limit : The bending radius of 30 μ m glass has exceeded 1.5mm, but the efficiency of ion exchange strengthening restricts the mass production speed. Self repairing coating (such as polysiloxane nano layer) may become a breakthrough point of the next generation.
The technological breakthrough path of Chinese enterprises directly points to the core: Dinghongrun Technology has achieved 30 μ m glass thinning, and the next goal is to improve the strength of 10 μ m ultra-thin glass to the level of mass production. When the thickness of glass is equal to the diameter of red blood cells (8 μ m), this micron level game is not only a technological contest, but also the ultimate contest of high-end manufacturing autonomy.
The ultimate enlightenment of precision manufacturing : On the scale of 30 microns, every precision leap of an angstrom is the symphony of material science, equipment control and process innovation – there is no miracle here, only a deep understanding of physical laws and ultimate control of engineering details.